Programmable infusion pumps are widely used in the intravenous administration of medication to patients in hospitals and elsewhere. They provide accurate long term medication without the need for constant nursing supervision.
It is frequently desirable to administer analgesic medication to a patient only when the patient deems it absolutely necessary. In order to do this without recourse to a nurse, special equipment has been developed by which the patient can trigger a predetermined infusion of analgesic medication at limited intervals.
Inasmuch as infusion pumps are fairly expensive items, it is desirable to provide an accessory which can convert an ordinary programmable infusion pump into a patient-controlled analgesia (PCA) device without the need of a separate pump for PCA purposes.